Also, you might want to check your punctuation, you're missing spaces after your periods in a lot of places.

If more instances are tested,their scents and effects will combine.

This does not need to be in the Procedures block. Stating that no more than a single instance may be tested at once is enough.

Removal of the instances of SCP-1359 from the testing vehicle is to be done by Level 4 personnel,equipped of full-face respirators,sterilizing carefully the vehicle and using an industrial filter bag to remove the instance.

Level 4 personnel, as defined in the Security Clearance Levels document, tend to be Site Directors. Why are they the only ones allowed to move the SCP? It's like requiring the president of a company to be around whenever someone makes a delivery. Also, more missing spaces.

Description: SCP-1359 is a collection of seven (7) disposable air fresheners shaped as a stylized evergreen tree (Abies alba),better known as “Little Trees”,usually marketed for cars,each labeled with a different name.

Contrary to popular belief, scientists are not shut-ins. It's perfectly fine to say, "SCP-XXXX is a set of seven (7) tree-shaped automobile air fresheners." Don't use ten words when five will do.

When any instance is located upon a roar-view mirror of a vehicle,it will enter in its active state,and will have distinct effects on human subjects,somehow linked to its name.

The effects will last as long as the instances are located upon the vehicle’s roar-view mirror.
When inactive,all the instances are completely odourless.

This should probably be "When an instance of SCP-XXXX is attached to the rear-view mirror of an automobile, […]" and then immediately followed by its actual function. Few things annoy a reader more than going into detail about how it activates without saying what it does when it activates.

On the posterior of any instance a list including all the name of the scents can be found.The list is the following.

Show Document XXXX-A

There is absolutely no reason to have this in a collapsible. I hate unnecessary collapsibles.

Addendum 1358-01: On the ██-██-████,Researcher ████████ found at his house’s doorstep a cardboard package from the █████ Oil Industries,containing all the instances of SCP-1359.

"Found on doorstep" is one of the lamest origins for a SCP. This is completely unnecessary and the SCP would be better without it.

Show document XXXX-B

This collapsible isn't necessary either.

Dear Mr. ████████,

Congratulations!For being our best costumer of the month,you won the whole limited edition of the “Muti-Fragrance Arbre Magique” Little Trees!
Visit our site http//www.█████oilindutries.com/██. for more upcoming prizes!

-Love, the whole █████ Oil Industries staff.

"customer", not "costumer". Also, why not just redact the entire URL? It's annoying with the blackboxes in it.

Researcher ████████ later affirmed that he never had any contact with the █████ Oil Industries.The site marked on the note package showed no results.

Still missing spaces.

Addendum XXXX-02: Further examinations of the instances showed that they are ██% formed by [DATA EXPUNGED],and this might explain their effects on human subjects.

This addendum is completely worthless, as you've expunged anything that might have been interesting to begin with.

Addendum XXXX-03: The following are the anomalous effects displayed by all the instances of SCP-XXXX when active.
[snip]

Ehhhh. Just not feeling all that interested, this is pretty much a vanilla magic item with random effects and zero context.

Summary

Generic magic item involving air fresheners that affect your mind with punctuation, spacing, and spelling errors littered throughout. I would downvote this as-is.

Eh, going straight to the Writing Help forum is fine. Chat isn't everyone's thing, and the Ideas forum is a lot more fallow than the Writing Help one. It's where I started out, and I doubt I'm the only one.

Highly edited,but since the effects are a problem too,I think I just wasted my time.And maybe I make it worse too.I suck at this.

You really need to stop making those spacing errors, or people are going to have trouble taking you seriously. Whenever you use a colon (:), comma (,), or period (.), you need to have a space after it.

Highly edited, but since the effects are a problem too, I think I just wasted my time. And maybe I make it worse too. I suck at this.

While you're at it, you should probably cut back on the "I suck" attitude too, no one wants to hear you cry.

Yeah,you are right.Anyway,despite the spacing errors and stuff,is there any chance this can be something good with some improvement?

*facepalm*

I can't take you seriously so long as you continue to butcher your sentences like this. I've already given you a long-form critique topped by the opinion that they're just not very interesting as-is. Whether you can get this to work or not depends on whether you can tell an interesting story with it.

The idea reminds me a bit of SCP-1975 (a hula girl figurine that produces various effect when installed in a car). In that case it's more interesting because the effects are related to actual car driving and there is a story behind it. If you keep the idea of air freshener I would suggest making them home freshener instead of car's.